Downsizing the K-CHA zeolite by a postmilling-recrystallization method for enhanced base-catalytic performance

Abstract

Herein, we report the preparation of potassium chabazite (K-CHA) zeolite nanocrystals with enhanced base-catalytic performance using a bead-milling and postmilling-recrystallization technique. Particles as small as 60 nm were produced by this approach. The surface area of the downsized K-CHA samples showed a significant improvement, increasing from 11 m² g⁻¹ to 65 m² g⁻¹. The catalytic activity of the K-CHA nanocrystals in the Knoevenagel condensation of benzaldehyde with ethyl cyanoacetate was found to be twofold higher than that of the raw and the milled samples, achieving 80% product yield within a reaction time of 60 min. In addition, the enhanced catalytic behavior of the K-CHA nanocrystals, despite possessing low surface area relative to the intermediate milled sample, is attributable to the postmilling-recrystallization step, which played a pivotal role in restoring the crystallinity to around 80%.